1. Field of the Invention
The present invention relates to stirrer lids for color cans equipping paint stirring machines and, in particular, to a stirrer lid of the type comprising, at its base, a frustoconical annular closure edge intended to be tightly applied against the corresponding upper opening rim of the color cans and which can be easily adaptable, for closing, to the various existing color cans which vary slightly in shape from one constructor to another. It also relates to the method of manufacturing these lids.
2. Discussion of the Prior Art
It is known that stirrer lids of this type permit automatic self-centering on the receiving color cans, that they make it possible to compensate for defects of the rim of the can, the possible oval of the rim, for example, by the wedging effect on closing and, finally, that they provide a rigid closure which is permanent over time and insensitive to the stirring vibrations, in contradistinction and to lids with a flexible seal device.
These stirrer lids are particularly suitable for the stirring of color cans mounted so as to be suspended from the stirring machines, but they may also be fitted onto machines with standing cans. They are cast in a single piece from a metal alloy, preferably Zamak, the frustoconical closure rim forming an integral part of the body of the lid. However, the dimensions of the opening edge of the cans, for a defined can capacity range (1, 3, 5 liters) vary slightly depending on their origin. The diameter of the opening edge of the cans may vary for the same capacity range, by 5%, from one constructor to another. Of course, it is possible to vary the depth to which the frustoconical rim of the lid is pressed onto the edge of the can, being applied against one or other of the inner and outer flanges of the annular rim of the collar bearing the closure edge of the can, or against its peripheral terminal shoulder, but these various possibilities permit only limited closure adaptation to the various paint cans existing on the market.
Adaptation of this type of lid to a defined series of color cans thus requires generally the production of a specific lid whose frustoconical rim is adjusted to the particular opening edge of said series. This production consequently requires the complete casting of a series of lids adapted to said series of cans. A change of mold, from one series to another, requires a relatively lengthy operation time (several hours) due to the extensive handling of the masses involved (several hundreds of Kg) for the lid mold and its heating to temperature and temperature stabilization before casting.